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NUCLEAR WEAPONS COLLATERAL DAMAGE EXAGGERATIONS: IMPLICATIONS FOR CIVIL DEFENSE 

Nigel Cook 




-r 



-O 



Joint Commission Report, 
Vol. VI, Document NP-3041 
Hiroshima 

Ashley W. Oughterson, et al. 

Medical Effects of_ Atom i c Bomb s, 

Army Institute of Pathology 

NP-3041 {Vol. VI), 1951. 

JOINT COMMISSION DATA FOR OVERALL 
SURVIVAL 

-G "UNSHIELDED" SCHOOL PERSONNEL 

-A "SHIELDED" SCHOOL PERSONNEL 

-# EXPOSED INSIDE CONCRETE BUILDINGS 



POINT 
NO. 

I 

2 
3 

4 
5 
6 

7 



BUILDING 
DESIGNATION 



NO. INDIVIDUALS 
EXPOSED 



POST OFFICE 400 ' 

TELEGRAPH OFFICE 301 

TELEPHONE OFFICE 474 

CITY HALL 2 16 

COMMUNICATIONS OFFICE 682 

BRANCH POST OFFICE 346 

PO. SAVINGS OFFICE 750 



Lower floors of Post Office were most occupied 
I I 



1.5 

RANGE. MILES 



2.5 



Figure 1: Dr Ashley W. Oughterson and other members of the Joint Commission for the Investigation of the Effects of the 
Atomic Bomb in Japan in 1951 produced a six volume report called Medical Effects of Atomic Bombs (U. S. Office of the Air 
Surgeon, and U. S. Army Institute of Pathology), summarizing research done into case histories for personnel in known 
locations in the open and within buildings at the time of the August 1945 nuclear explosions in Hiroshima and Nagasaki. 
Volume VI (document NP-3041) contained the data shown above, proving the immense increase in survival due to protective 
actions against easily-shielded thermal and nuclear radiation. This data is vital for civil defense but is not being applied to the 
analysis of casualty rates from nuclear explosions for civil defense, since propaganda from America and Japan instead presents 
an "average" casualty curve, which covers up and obfuscates the differences in survival rates in different situations. In 
particular, the curves above disprove the "uniformly lethal firestorm" myth. Blast survivors were not all killed in the firestorm. 

The Effects of the Atomic Bomb on Hiroshima, Japan, Report No. 92 
(Vole* I- III), U. S, Strategic Bombing Survey, Physical Damage Divi- 
sion; May, 1947. 

Effects of the Atomic Bomb on Nagasaki, Japan , Report No. 93 
(Vols. I- III), U # S. Strategic Bombing Survey, Physical Damage Divi- 
sion; June, 1947* 



Figure 2: The U. S. Strategic Bombing Survey classified its detailed reports 92 and 93 on the nuclear explosions in Hiroshima 
and Nagasaki "Secret", and instead published an obfuscating summary report which omits the evidence that the firestorm in 
Hiroshima was due to the overturning of charcoal cooking braziers in bamboo and paper screen filled wooden houses, not 
thermal radiation. This caused anti-civil defense propaganda to falsely associate the firestorm radius to the thermal radiation 
exposure at that radius, instead of correctly associating it to the blast effect in overturning obsolete charcoal braziers. Report 
92 on Hiroshima actually states (pages 4-6, May 1947): "Six persons who had been in reinforced-concrete buildings within 
3,200 feet [975 m] of air zero [i.e., (975 2 - 600 2 ) 1/2 = 770 m ground range] stated that black cotton black-out curtains were 
ignited by flash heat... A large proportion of over 1,000 persons questioned was, however, in agreement that a great majority of 
the original fires were started by debris falling on kitchen charcoal fires...." 



The unclassified 1957 U. S. Department of Defense book The Effects of Nuclear Weapons obfuscated this evidence, vaguely 
stating on pages 322-3: "Definite evidence was obtained from Japanese observers that the thermal radiation caused thin, dark 
cotton cloth, such as the black-out curtains that were in common use during the war, thin paper, and dry, rotted wood to catch 
fire at distances up to 3,500 feet (0.66 mile) from ground zero (about 35 calories per square centimetre)." Thus, black coloured 
curtails, thin paper and dry, rotted wood, needed 35 cal/cm 2 to ignite in the coastal cities of Japan during August when there 
was high humidity. White curtains, which are more common now that air raid precautions no longer demand black window 
curtains, require much higher thermal exposures for ignition than black curtains. 

TOTAL MORTALITY CURVES FOR NAGASAKI 




8 10 
Ovtrprtuur* (ptl) 



20 



40 



60 



60 K>0 



TOTAL MORTALITY CURVES FOR HIROSHIMA 



100 




8 10 

Ovarprttiurt (pti) 



ZO 



40 



60 



60 100 



Figure 3: The Peak overpressures for casualties from all effects of nuclear explosions. Source: L. Wayne Davis, Prediction of 
Urban Casualties and the Medical Load from a High-Yield Nuclear Burst, Dirkwood Corporation paper DC-P-1060-1 (1968). 
The data assumes a yield of 22 kt for Nagasaki (close to 21 kt used in DS02) and 12.5 kt for Hiroshima (lower than 16 kt used 
for DS02). Correcting the yields increases the overpressures for observed mortality, reconciling much low peak overpressure 
data for both cities. Small differences occur due to different neutron radiation outputs and the firestorm in Hiroshima. 



Peak overpressures for casualties from all effects of nuclear explosions. Source: L. Wayne Davis, Prediction of Urban 
Casualties and the Medical Load from a High-Yield Nuclear Burst, Dirkwood Corporation paper DC-P- 1060-1 (1968) 



Explosion 

Nagasaki (22 kt nuclear air burst over city, 
1945). Below 16 psi peak overpressure, the 
lower floors of buildings were subjected to 
the horizontal Mach stem blast wave, while 
above 16 psi buildings were subject to 
regular reflection (downward, radial incident 
blast, then the ground-reflected blast wave). 

Texas City Disaster (0.67 kt non-nuclear 
explosion in Texas City, 1947). Peak 
overpressures for given casualties are higher 
than at Nagasaki, because of the lack of 
initial nuclear radiation; although fires were 
ignited by hot debris from an exploding ship. 

Hiroshima (16 kt nuclear air burst over city, 
1945). Peak overpressures are underestimates 
based on 12.5 kt (rather than 16 kt) yield; a 
firestorm contributed to the fatalities shown, 
because some people were trapped in fires. 



Building type 

Wood-frame 

Outside but in thermal flash 
shadow (no burn) 
Light steel frame 
Seismic reinforced concrete, 
lower floors 
Underground shelters 
Wood-frame 
Light steel frame 
Outside but in thermal flash 
shadow (no burn) 
Heavy steel frame and non- 
seismic reinforced concrete 
Wood-frame 

Outside but in thermal flash 
shadow (no burn) 

Light steel frame 

NAGASAKI 



10% killed 


50% killed 


90% killed 


10 psi 


15.6 psi 


18 psi 


12.5 psi 


16 psi 


19 psi 



13 psi 
12.5 psi 

22 psi 
9.0 psi 



17.5 psi 
32 psi 

55 psi 

22.5 psi 



20 psi 
51 psi 

N/A 
30 psi 




30.6 psi 46 psi 

. p p 



11-14 psi 

7.0 psi 
9.0 psi 

10.5 psi 



40 psi 

12.2 psi 
13 psi 

13 psi 



70 psi 

13.5 psi 
13.5 psi 

13.5 psi 




40 so 60 

Area Burned (percent) 

Figure 4: The Dirkwood Corporation report Analysis of Japanese Casualty Data, DC-FR-1054, AD653922 (1966), gives the 

basic survival data for 35,099 case histories of personnel exposed to nuclear explosions over cities in Japan, August 1945 

(24,044 at Hiroshima and 1 1,055 at Nagasaki). This graph shows the effects mortality to outdoor personnel in terms of the 

percentage of body area (easily derived from the "rule of nines") subjected to thermal blistering (2 nd degree) and surface 

charring (3 rd degree) burns. Contrary to popular propaganda, the mortality depended on the body area burned, since shadows 

from clothing, buildings, trees, fences, vehicles, people, and terrain provided substantial protection against thermal radiation. 

In Hiroshima, the Dirkwood data (DC-FR-1054, Fig. 34) shows that the distance from ground zero for 50% survival ranged 
from 140 metres for the lower floors of earthquake- standard concrete buildings to 730 metres for vehicles (street cars/trolley 
buses/trams) and 880 metres for wood-frame dwellings. Outdoors, casualty rates depended essentially on thermal radiation 
exposure in combination with initial nuclear radiation (which suppressed the white blood cell count during burn healing, 
allowing fatal infections in many cases), and its shadowing by clothing, trees, buildings, fences, terrain, vehicles, etc., rather 
than blast. People outdoors in thermal shadows were not burned and survived high peak overpressures like those in buildings, 
as shown. Most people outdoors moved out of shadows into a clear radial line of sight to watch the B-29 aircraft and saw the 
bomb fall, unaware of the danger, and were flash-burned in silence before the blast wave arrived and knocked them down. 
Mortality for people outdoors without thermal shielding was 10% for 12 cal/cm 2 , 50% for 16 cal/cm 2 , and 90% for 18 cal/cm 2 
(these figures apply to the light summer clothing worn in August and include enhancements due to synergism of burns with 
initial nuclear radiation). 



At 3.05 km ground range in Nagasaki, 43% had 2 nd degree burns (blistering) and 5% had 3 rd degree burns (charring), although 
even light clothing offered complete protection here, so the body area burned was small and recovery was possible in all cases. 
There was no significant nuclear radiation at that distance to accompany the thermal flash burns and delay or prevent recovery 
from the burns. At 1.86 km ground range in Nagasaki, there was 10% mortality to persons outdoors without thermal 
shadowing, due to the 53% of cases having 3 rd degree burns and 36% having 2 nd degree burns, an average total body burned 
area of 20% (DC-FR-1054, Figs. 28 and 29). A rate of 50% mortality for unshielded persons outside in Nagasaki occurred at 
1.37 km from ground zero, where 72% of cases had 3 rd degree and 18% had 2 nd degree burns, with an average total body 
burned area of 38%. The reason for the increase in area from 20% average area burned at 1.86 km (10% killed) to 38% 
average area burned at 1.37 km (50% killed) in Nagasaki was simply that the burns were more likely to occur under light 
summer clothing as the thermal radiation increased. At low thermal exposures, a low protection factor by clothing is sufficient 
to stop any burns under clothing. 



100 



EXERCISE ARC 
CASUALTIES FROM 

(ALL IN HOUSES) 



GROUND BURST 



UJ 



< 
2 

UJ 



o 

QC 
UJ 
Q. 



2 TONS OF TNT BLAST 
2.4 TONS OF TNT TOTAL 




io 



20 



30 



40 



50 



60 



70 



80 



90 



100 



DISTANCE FROM 6.Z. (METRES) 



World War I 
(no Civil 
Defence) 



STANDING IN 
THE OPEN OR 
IN A STREET 



World War II lessons for civil defence in Britain 

THE RISK OF BECOMING A CASUALTY 

June and July 1917 World War I London 
bombings = 121 casualties per ton of bombs 

World War II = 2 casualties per ton of bombs, 
60 times fewer than the rate in World War I 



LYING DOWN 

IN THE OPEN 

OR IN A 

STREET 



(Duck and Cover) 



LYING BEHIND 
LOW COVER OR 
IN A DOORWAY 




World War II 
Civil Defence 

i 

IN TRENCHES, 

GOOD SURFACE 

SHELTERS, OR 

STRUTTED 

BASEMENTS 



SHELTER IN A 

BRICK HOUSE 

AWAY PROM 

WINDOWS 



IN SHELTER 



Figure 5: The value of duck and cover as protection against hurricane force blast winds and flying debris was proved in 
Britain during the Blitz bombing. The blast casualty rates to unprotected personnel in cities during bombing in World War I 
was reduced by simple countermeasures during World War II. Sources: U. K. Home Office publications, "Exercise Arc" 
(1959), "History of the Second World War: Civil Defence" (Terrence O' Brien for H. M. Stationery Office, 1955), and "Basic 
Methods of Protection Against High Explosive Missiles" (1949). (1.2 tons of TNT = 2.4 tons nuclear yield for 50% blast.) 



H N r i H N T I AL 

DEPARTMENT OF THE ARMY TECHNICAL MANUAL TM 23200 

DEPARTMENT OF THE NAVY OPNAV INSTRUCTION 03400.1B 

DEPARTMENT OF THE AIR FORCE AFL 136*1 

MARINE CORPS PUBLICATIONS NAVMC 1104 REV 



CAPABILITIES 

OF 

ATOMIC WEAPONS (U) 




Prepared by 
Armed Forces Special Weapons Project 



DEPARTMENTS OF THE ARMY, THE NAVY 
AND THE AIR FORCE 

REVISED EDITION NOVEMBER 1957 



6.1c (3) 

Table 0- /. Estimated Casualty Production in Structures 
for Various Degrees of Structural Damage 



1-2 story brick homes (high ex- 
plosive data): 

Severe damage 

Moderate damage 

Light damage 

Reinforced -cod Crete buildings (Jap- 
anese data, nuclear) : 

Severe damage 

Moderate damage 

Light damage 



Killed 
outright 



Percent 

25 
<5 



Serious 
Injury 
(bospi- 
ulita* 
tioo) 



Percent 

20 

10 

<5 



100 

10 

<5 



I 



15 
<5 



Light 
injury 
(No bos* 
planta- 
tion) 



10 

5 

<5 



20 
15 



Note. These percentages do not include the casualties which may result 
from tits, asphyxiation, and other causes from failure to extricate trapped 
personnel. The numbers represent the estimated percentage of casualties 
expected at the mirlmnm range where the specified structural damage occurs. 



6.S Thermal Injury 

a. Introduction. Before attempting to predict 
the number of thermal casualties which occur in a 
given situation, it is necessary to recognize the 
factors which influence the number and distribu- 
tion of casualties to be expected. These factors 
include — the distribution or deployment of per- 
sonnel within the target area, whether proceeding 
along a road, in foxholes, standing or prone, in the 
open or under natural cover; orientation with 
respect to the bomb; clothing, including number 
of layers, color, weight, and whether the uniform 
includes helmets, gloves, or other devices which 
might protect the bare skin, such as flash creams; 
and natural shielding. 



WiriPEHTUL 



6-3 



F I GURE 5-2 

_, . „ . 1 KT 100 KT 10 MT 

Thermal effects: (cof/tm>) 

Second degree bare skin burn.. 4 5. 1 9. 1 

Army khaki summer uniform 

destruction 18 31 56 

Navy white uniform destruc- 
tion 34 60 109 

Blast effects (in the Mach region) : 
Severe damage to overpressure 
sensitive structures: 

Blast-resistant designed (PS/ owrpmmro 

buildings 50 40 35 

Reinforced concrete build- 
ings 10.5 9.5 9 

Monumental wait bearing 

buildings 20 15 15 

Wood frame housing 3 3 3 

Window pane breakage 0.5 0.5 0.5 

Severe damage to dynamic pres- 
sure sensitive structures: 

Light steel frame single iPSt rfmomw pra$ure) 

story buildings 4.5 2 0.9 

Heavy steel frame single 

story buildings 6 3 1.5 

Steel frame multistory 

buildings 7.5 2.5 0.9 

150'-250' span truss 
bridges 50 8 5.5 

5-12 

tub ^tOHUULNTMI 

b. Primary Radiant Energy Burns. Damage to 
bare skin through the production of burns may be 
directly related to the radiant exposure and the 
rate of delivery of the thermal radiation, both of 
which are yield dependent. For a given total ex- 
posure, as the weapon yield increases, the thermal 
radiation is delivered over a longer period of time 
and thus at a lower rate. This allows energy loss 
from the skin surface by conduction to the deeper 
layers of the skin and by convection to the air. 

c. Burns Under Clothing. Clothing reflects and 
absorbs much of the thermal radiation incident 
upon it and thereby protects the wearer against 
flashburn. In some cases, the protection is com- 
plete, but in many cases it is partial in that cloth- 
ing merely reduces the severity of injury rather 
than preventing it. At large radiant exposures, 
there is the additional possibility that the glowing 
or ignition of the clothing could deliver additional 
energy to the skin, thereby causing a more severe 
injury than bare skin would have suffered. 

Table 6-2. Critical Radiant Exposures for Burns Under 

Clothing 

(Expressed in calf cm 1 incident on outer surface of cloth) 



Clothing 



Summer Uniform 
(2 layers) 

Winter Uniform. 
(4 layers) 



Burn 1 KT 100 KT 10 MT 



1° 
2° 
1° 
2° 



8 
20 
60 
70 



11 
25 

80 
90 



14 

35 

100 

120 



Note. These values are sensitively dependent upon many variables which 
are not easily denned (see test), and are probably correct within a factor 
of two. 



6-4 



Figure 6: WWII blast and thermal casualty data was classified Confidential in TM 23-200, Capabilities of Atomic Weapons. 



The Eiiects oi 
Atomic Weapons 

PREPARED FOR AND IN COOPERATION WITH THE U. S. DEPARTMENT OF 
DEFENSE AND THE U. S. ATOMIC ENERGY COMMISSION 

Under the direction of the 
LOS ALAMOS SCIENTIFIC LABORATORY 

Los Alamos, New Mexico 




Revised September 1950 



BOARD OF EDITORS 
J, O. Hirschfelder, Chairman 



Arnold Kramish 



David B. Parker 
Ralph Carlisle Smith 



Samuel Glasstone, Executive Editor 



For sale by the Superintendent of Documents, U. S. Government Printing Office 
Washington 25, D. C. - Price 31.25 (paper bound) 

RADIOACTIVE CONTAMINATION FROM UNDERWATER BURST 279 

8.91 From measurements made at the time of the Bikini "Baker" 
test, it has been possible to draw some general conclusions with regard 
to the integrated or total radiation dosage received at various dis- 
tances from surface zero. 



E 

in 




(miles) 



Figure 8,91a. Contours for various integrated radiation dosages due to base 
surge from underwater burst. 



CHAPTER I 1 

PRINCIPLES OF AN ATOMIC EXPLOSION 

A. INTRODUCTION 
Characteristics of an Atomic Explosion 

1.1 The atomic bomb is a new weapon of great destructive power. 
It resembles bombs of the more conventional type in so far as its 
explosive effect is the result of the very rapid liberation of a large 
quantity of energy in a relatively small space. But it differs from 
other bombs in three important respects: first, the amount of energy 
released by an atomic bomb is a thousand or more times as great as 
that produced by the most powerful TNT bombs; second, the explo- 
sion of the bomb is accompanied by highly-penetrating, and deleteri- 
ous, invisible rays, in addition to intense heat and light; and third, 
the substances which remain after the explosion are radioactive, 
emitting radiations capable of producing harmful consequences in 
living organisms. It is on account of these differences that the effects 
of the atomic bomb require special consideration. 

1.2 A knowledge and understanding of the mechanical and radia- 
tion phenomena associated with an atomic explosion are of vital im- 
portance. The information may be utilized, on the one hand, by 
architects and engineers in the design of structures ; while on the other 
hand, those responsible for civil defense, including treatment of the 
injured, can make preparations to deal with the emergencies that may 
arise from an atomic explosion. 

1.3 During World War II many large cities in England, Germany, 
and Japan were subjected 16 terrific attacks by high-explosive and 
incendiary bombs. Yet, when proper steps had been taken for the 
protection of the civilian population and for the restoration of services 
after the bombing, there was little, if any, evidence of panic. It is 
the purpose of this book to state the facts concerning the atomic 
bomb, and to make an objective, scientific analysis of these facts. 
It is hoped that as a result, although it may not be feasible completely 
to allay fear, it will at least be possible to avoid panic. 



i Material contributed by G. Gamow, S. Glasstone, J. O. Hirschfelder. 



280 



RESIDUAL NUCLEAR RADIATIONS AND CONTAMINATION 







lOOr 



400r 



lOOOr 



Figure 8.91b. 



(miles) 



Contours for various integrated radiation dosages due to con- 
tamination from underwater burst. 



Figure 7: During Operation Crossroads on 25 July 1946 an underwater nuclear explosion occurred, Baker (23.5 kt at 90 feet 
depth in 180 feet of water within Bikini Lagoon, Pacific). The mushroom cloud consisted of small sea-water droplets. After 
about 12 seconds the "column" or stem of the mushroom rapidly collapsed to form a radioactive wind-carried surface "base 
surge" mist, and rapidly spread out, enveloping and irradiating ships nearby. Then the water droplets in the mushroom cloud 
head fell back in a "rainout" which reached the surface about one minute after detonation, contaminating the ships. The wind 
affected both the base surge and the cloud rainout. In 1950 the dose patterns from each phenomenon were published (above). 



The Effects of 
Nuclear Weapons 



GAMMA RAYS 



-ssr 




Samuel Glasstone 
Editor 



Prepared by the 

UNITED STATES DEPARTMENT OF DEFENSE 

Published by the 

UNITED STATES ATOMIC ENERGY COMMISSION 

June 1957 



For sale by the Superintendent of Documents, U. S. Government Printing Office 
Washington 25, D. C. - Price $2.00 (P*P« bound) 



ATTENUATION OF RESIDUAL NUCLEAR RADIATION 



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THICKNESS (INCHES) 

Figure 8.47. Attenuation of initial gamma radiation. 

PROTECTIVE MEASURES 



Figure 9.36. Attenuation of fission product radiation. \r 014-0 M T J 



12.60 In the event of a surprise attack, when there is no oppor- 
tunity to take shelter, immediate action could mean the difference be- 
tween life and death. The first indication of an unexpected nuclear 
explosion would be a sudden increase of the general illumination. It 
would then be imperative to avoid the instinctive tendency to look at 
the source of light, but rather to do everything possible to cover all 
exposed parts of the body. A person inside a building should imme- 
diately fall prone and crawl behind or beneath a table or desk. This 
will provide a partial shield against splintered glass and other flying 
missiles. No attempt should be made to get up until the blast wave 
has passed, as indicated possibly by the breaking of glass, cracking 
of plaster, and other signs of destruction. The sound of the explosion 
also signifies the arrival of the blast wave. 

12.61 A person caught in the open by the sudden brightness due 
to a nuclear explosion, should drop to the ground while curling up 
to shade the bare arms, hands, neck, and face with the clothed body. 
Although this action may have little effect against gamma rays and 
neutrons, it might possibly help in reducing flash burns due to thermal 
radiation. The degree of protection provided will vary with the 
energy yield of the explosion. As stated in § 7.53, it is only with 
high-yield weapons that evasive action against thermal radiation is 
likely to be feasible. Nevertheless, there is nothing to be lost, and 
perhaps much to be gained, by taking such action. The curled-up po- 
sition should be held until the blast wave has passed. 

12.62 If shelter of some kind, no matter how minor, e. g., .in a door- 
way, behind a tree, or in a ditch, or trench can be reached within a 
second, it might be possible to avoid a significant part of the initial 
nuclear radiation, as well as the thermal radiation. But shielding 
from nuclear radiation requires a considerable thickness of material 
and this may not be available in the open. By dropping to the ground, 
some advantage may be secured from the shielding provided by the 
terrain and surrounding objects. However,, since the nuclear radia- 
tion continues to reach the earth from the atomic cloud as .it rises, the 
protection will be only partial. Further, as a result of scattering, the 
radiations will come from all directions. 



Figure 8: Data on gamma radiation shielding and civil defence against fires was published in The Effects of Nuclear Weapons. 



The Effects of 
Nuclear Weapons 





Samuel Glasstone 
Editor 



Revised Edition 
Reprinted February 1964 



Foreword 

This book is a revision of "The Effects of Nuclear 
Weapons" which was issued in 1957. It was prepared 
by the Defense Atomic Support Agency of the Department 
of Defense in coordination with other cognizant govern- 
mental agencies and was published by the U.S. Atomic 
Energy Commission. Although the complex nature of 
nuclear weapons effects does not always allow exact 
evaluation, the conclusions reached herein represent the 
combined judgment of a number of the most competent 
scientists working on the problem. 

There is a need for widespread public understanding 
of the best information available on the effects of nuclear 
weapons. The purpose of this book is to present as 
accurately as possible, within the limits of national 
security, a comprehensive summary of this information. 



Mj?^*£~ 



Prepared by the 

UNITED STATES DEPARTMENT OF DEFENSE 

Published by the 

UNITED STATES ATOMIC ENERGY COMMISSION 

April 1962 



For sale by the Superintendent of Documents, U.S. Government Printing Office 
Washington 25, D.C. - Price £3.00 (paper bound) 



Secretary of Defense 

Chairman 
Atomic Energy Commission 




IDEALIZED FALLOUT PATTERNS 



445 



SUMMARY 



661 



190 
180 - 
170 " 
160 
150 - 



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§ 130 

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" 4; 



20 10 10 20 20 10 10 20 20 10 10 
DISTANCE FROM GROUND ZERO (MILES) 

1 HOUR 6 HOURS 18 HOURS 

Figure 9.67b. Total-dose contours from early fallout at 1, 6, and 18 hours after 
surface burst with 1-megaton fission yield (15 mph effective wind speed). 



12.78 In the event that shelters are not available, certain evasive 
actions may prove helpful at distances where the immediate effects 
are least severe. By instantly falling prone and covering exposed 
portions of the body or getting behind opaque objects, much of the 
thermal radiation may be avoided, especially in the case of large-yield 
weapons. Under no circumstances should an individual look in the 
direction of the fireball. Staying behind thick walls or lying in a deep 
ditch may help to avoid initial nuclear radiation. All of the above 
actions will also help to decrease the possible danger from the blast 
wave. Moreover, persons should avoid areas which have frangible 
materials, such as window glass, plaster, etc., which may become 
flying debris by the action of the blast. 

12.79 After the immediate effects of the nuclear explosion are over, 
certain acts are required to minimize the hazards of the early fallout 
and from the fires which may result from thermal radiation and second- 
ary blast, effects. First, if small fires can be quickly extinguished, 
extensive conflagrations may be prevented. This must be accom- 
plished before the arrival of the fallout or in areas of low radioactivity 
levels. Some protection from the fallout may be secured in the base- 
ments of buildings or in a quicldy constructed shelter, such as is 
described in § 12.55. It is important to keep from coming into physi- 
cal contact with the fallout particles, and to prevent contamination 
of food and water sources. Monitoring equipment should be used to 
determine areas which have safe radiation levels and decontamination 
efforts can proceed to recover necessary equipment, buildings, and 
areas. 

Conclusion 

12.80 Much of the discussion presented in earlier sections of this 
chapter have been based, for simplicity, on the effects of a single 
weapon. It must not be overlooked that in a nuclear attack some 
areas may be subjected to several bursts. The basic principles of 
protection would remain unchanged, but protective action against all 
the effects of a nuclear explosion — blast, thermal radiation, initial 
nuclear radiation, and fallout — would become even more important. 



THERMAL KAIHATIO-N EFFECTS 



-32T- 



INCENDIARY EFFECTS 



-34t- 




Figure 7.33a. Thermal effects on wood-frame house 1 second after explosion 
(about 25 cal/sq cm). 




Figure 7.33b. Thermal effects on wood-frame house about % second later. 
342 THERMAL RADIATION AND ITS EFFECTS 



KflMlMi Li'ti J 



Figure 7.57. Wooden test houses before exposure to a nuclear explosion, Nevada 
Test Site. 




USE CLASS 


NUMBER OF TRANSIENT EXTERIOR 
IGNITION POINTS PER ACRE 


WHOLESALE 
DISTRIBUTION 

SLUM RESIDENTIAL 

NEIGHBORHOOD 
RETAIL 

POOR RESIDENTIAL 

SMALL 
MANUFACTURING 

DOWNTOWN RETAIL 

GOOD RESIDENTIAL 

LARGE 
MANUFACTURING 


5 10 15 20 25 3 

1 1 1 1 I 







T | 












-: : v : "- ; :' :V -'v'-.;-;^ / : ".'/.-] 








;\( : 'v-" -".r, : * 


■ : H 






.-■; ; -' '•■•-'."• 1 






mm 


mm 

Z3 



Figure 7.58. Wooden test houses after exposure to a nuclear explosion. 



Figure 7.55. Frequency of exterior ignition points for various areas in a city 

the formation of a significant fire, capable of spreading, will require 
appreciable quantities of combustible material close by, and this may 
not always be available. 

7.57 The fact that accumulations of ignitable trash close to a 
wooden structure represent a real fire hazard was demonstrated at 
the nuclear tests carried out in Nevada in 1953. In these tests, 
three miniature wooden houses, each having a yard enclosed with a 
wooden fence, were exposed to 12 calories per square centimeter of 
thermal radiation. One house, at the left of Fig. 7.57, had weathered 
siding showing considerable decay, but the yard was free from trash. 
The next house also had a clean yard and in addition, the exterior 
siding was well maintained and painted. In the third house, at the 
right of the photograph, the siding, which was poorly maintained, 
was weathered, and the yard was littered with trash. 

7.58 The state of the three houses after the explosion is seen in 
Fig. 7.58. The third house, at the right, soon burst into flame and 
was burned to the ground. The first house, on the left, did ignite 
but it did not burst into flame for 15 minutes. The well maintained 
house in the center with the clean yard suffered scorching only. It 
is of interest to recall that the wood of a newly erected white-painted 

INCENDIARY EFFECTS 343 

house exposed to about 25 calories per square centimeter was badly 
charred but did not ignite (see Fig. 7.33b). 

7.59 The value of fire-resistive furnishing in decreasing the num- 
ber of ignition points was also demonstrated in the tests. Two 
identical, sturdily constructed houses, each having a window 4 feet 
by 6 feet facing the point of burst, were erected where the thermal 
radiation exposure was 17 calories per square centimeter. One of 
the houses contained rayon drapery, cotton rugs, and clothing, and, 
as was expected, it burst into flame immediately after the explosion 
and burned completely. In the other house, the draperies were of 
vinyl plastic, and rugs and clothing were made of wool. Although 
much ignition occurred, the recovery party, entering an hour after 
the explosion, was able to extinguish the fires. 

7.60 There is another point in connection with the initiation of 
fires by thermal radiation that needs consideration. This is the 
possibility that the flame resulting from the ignition of a combustible 
material may be subsequently extinguished by the blast wind. It 
was thought that there was evidence for such an effect from an obser- 
vation made in Japan (§ 7.67), but this may have been an exceptional 
case. The matter has been studied, both in connection with the 
effects in Japan and at various nuclear tests, and the general con- 
clusion is that the blast wind has no significant effect in extinguishing 
fires (§ 7.68). 

Spread of Fires 

7.61 The spread of fires in a city, including the development of 
a "fire storm" to which reference is made in § 7.75, depends upon a 
variety of conditions, e.g., weather, terrain, and closeness and com- 
bustibility of the buildings. Information concerning the growth and 
spread of fires from a large number of ignition points, such as might 
follow a nuclear explosion, and their coalescence into large fires (or 
conflagrations) is limited to the experience of World War II incendiary 
raids and the two atomic bomb attacks. There is consequently some 
uncertainty concerning the validity of extrapolating from these limited 
experiences to the behavior to be expected in other cities. It appears, 
however, that if other circumstances are more-or-less the same, an 
important criterion of the probability of fire spread is the distance 
between buildings. It is evident, from general considerations, that 
the lower the building density or "built-upness" of an area, the less 
will be the probability that fire will spread from one structure to 
another. Furthermore, the larger the spaces between buildings the 
greater the chances that the fire can be extinguished. 



Scattered 
points ranging 
fron 0.025 to 
0,042 




Severe Blast and 
fire daatage to 

sttui.-ti.res within 



Results of the Naval Medical Research Institute (ISnsiRI) su^ey perfonned m Hiroshima on 
November 1-2, 1945, showing residual radiation levels of 0.069 miUiroentgen per hour (mR/hr) in the 
vicinity of ground zero and 0.011 mR/hr at the outermost contour. Source: DNA 5512F. 

Bomb Sites, NMRI-160A) documents a readual exposure rate of 0.081 mR/hr at the hypocenter as well as spot 
measurementeofOaiM^i^ These values are not 

represented on the map in DNA 55 12F. v*mc* are not 

Figure 9: Residual radioactivity due to fallout and neutron induced activity in Hiroshima was collected in detailed surveys 
during 1945 that were kept secret. Hiroshima and Nagasaki have been continuously occupied! The two 16-21 kt air bursts at 
about 600 metres over the cities produced no significant local fallout. 




DNA EM-1 
PART I 

DEFENSE NUCLEAR AGENCY EFFECTS MANUAL NUMBER 1 

CAPABILITIES 

OF 

NUCLEAR WEAPONS 

1 JULY 1972 



HEADQUARTERS 
Defense Nuclear Agency 
Washington, D.C. 20305 



wTC" 



Contoun for Boat* in the Transition Zona 



MB RlPre 5-43 may be used to determine 
whether or cot a bunt is in the transition zone, 
I*, below a height of bunt of 10OW " feet. 
Bunt heights below the curve in Figure 5-43 'are 
the transition zone. Bunt heights above the 
curve are air bunts. In some situations, it may 
be &±z**2 tc consider bunts below IWW°* 
feet to be in the transition zone for conservative 
estimates. The means for doing this are discussed 
below. When a bunt occurs in the transition 
zone, an approximation of the resulting fallout 
contamination patterns may be obtained by 
multiplying the dose rate contour values for a 
contact surface bunt weapon of the same yield 
by an adjustment factor from Figure 5-44. The 
curves of Figure 5-44 were constructed under 
the assumption that the ratio of the dose rate 
values from a bunt in the transition zone to the 
dose rate values for the same contour from a 
surface bunt are proportional to the ratio of the 
volume of a segment of a sphere intercepted by 
the ground surface to the volume of the hemi- 
sphere, where the radius of the sphere is 
lOW 035 feet, Le., 



2x10* 



where lib the actual height of burst in feet, and 
W is th e total weapon yield in kilotons. 
A^R In view of the lack of data from bursts 
inffif transition zone over a land surface, a more 
conservative estimate may be desired. In this 
case, the height of burst for the upper hmit of 
the transition zone is taken to be 1 SOW * 4 feet 
The adjustment factor to be applied to dose rate 
values for the same conn 
burst of the same yield can be i 



KjfafKfr) 



I.l7x 10 7 

fl| Example ^P 

^Hstvtn: A hypothetical weapon with a total 
yield of 600 kt, of which 300 H result* from 
fission, is burst 560 feet over a land surface with 
1 knot effective wind conditions. 

Find: The contour parameten for a dose 
rate of 15 rads/hr at H + l hour reference time 



Solution: From Figure 5-43. a 600 kt 
i burst below about 940 feet would be in 
the transition zone. A height of burst of 560 
feet is less than three quartan of the limiting 
altitude of the transition, so fallout is the only 
residual radiation to be considered. The 15 reds/ 
hr contour for a fission yield to total yield ratio 
of 200/600 * 1/3 corresponds to the contour for 
15 * 1/3 * 45 rads/hr for a weapon of 600 kt 
fission yield. The dose rate over reasonably level 
terrain is about 70 percent of that over an ideal 
smooth plane. Thus, the ideal smooth ptane con- 
l for this weapon burst on the 



£y = 64 radWhr. 

From Figure 5-44 (or from the normal adjust- 
ment factor equation given above) the height of 
bunt adjustment factor for a 600 kt weapon 
bunt at 560 feet is 0.21. Therefore, the desired 
contour parameten can be obtained by entering 
Figures 5-28, 5-31. 5-34, and 5-37 with a yield 
of 60T kt and readmg me parameter values cor- 
responding to an //+ 1 hour dose rate of 

64 



0.21 



• 300 rads/hr. 



Figure 10: By the time cloud stem debris is carried into the fireballs of air bursts, the fission products and weapon residue 
have long since condensed into solid particles within a toroidal shaped vortex. Incoming dust enters the hole in the ring and up 
over the top, cascading back without mixing with the condensed fission products, so no significant local fallout is formed. 



COMPARISON of 
FALLOUT CONTOURS 




SN.HI 



-\lOHMiy- 



5MT BURST 1KT BURST 

Figure 11: Pacific 5 Mt 87% fission surface burst Redwing-Tewa (1956) and Nevada 1.2 kt 100% fission surface burst Jangle- 
Sugar (1951), from Dr Terry Triffet's testimony to the Special Subcommittee on Radiation of the Joint Committee on Atomic 
Energy, U. S. Congress, Biological and Environmental Effects of Nuclear War, hearings on 22-26 June 1959. Failures in 
fallout predictions at both Nevada and Pacific tests were due to the fact that the shots had to occur under unstable wind 
conditions, since the prevailing winds in both cases blew towards the east (towards inhabited St George and Rongelap Atoll). 



A Fallout Forecasting Technique With 

Results Obtained at the Eniwetok Proving 

Ground, USNRDL-TR-139, E. A. Schuert, 

United States Naval Radiological Defense 

Laboratory 

Updated from WT-1317 (1961) 



Comparison of fallout forecast with test results 




PARAMETER ASSUMPTIONS USEO 

1 CLOUD TOP: 90.000 FT 

2 CLOUD BASE 50,000 FT 

3 CLOUO DIAMETER 60 N MILES 

4 HOT LINE FALLOUT^ FROM 50-60,000 FT 

METEOROLOGICAL PARAMETERS 

I TIME VARIATION OF THE WIND FIELD 






TEWA 
SURFACE ZERO' 



Figure 12: The accurate Redwing-Tewa (1956) fallout prediction of the hotline and high-intensity areas were made using a 
hand fallout forecasting technique by Edward A. Schuert aboard ship under simulated combat conditions. Schuert explained 
why fallout prediction was hard in his report A Fallout Forecasting Technique with Results Obtained at the Eniwetok Proving 
Ground (USNRDL-TR-139, 1957): "proper firing conditions, which required winds that would deposit the fallout north of the 
proving ground, occurred only during an unstable synoptic situation of rather short duration." 



R/hrat 1 hour 




10 R/hr at 1 hour 



1.2 kt 'Sugar' surface burst 




1.2 kt 'Uncle' burst at 5.2 m depth 



Figure 13: Dr Albert D. Anderson's U. S. Naval Radiological Defense Laboratory computerized "Dynamic Fallout Model" in 
1959 reproduced the Jangle-Sugar (1951) fallout pattern with sufficient accuracy for civil defense using only shot-time winds 
(The NRDL Dynamic Model for Fallout from Land-Surface Nuclear Bursts, USNRDL-TR-410). At the June 1959 U. S. 
Special Subcommittee on Radiation hearings, Biological and Environmental Effects of Nuclear War, the fallout research 
project officer for Redwing, Dr Terry Triffet, testified (p. 110) that wind shear and instability (variations over short intervals of 
time) were characteristic of the Pacific testing area: "... the winds over the Eniwetok Proving Grounds have a tendency to vary 
more than the winds over the United States ..." Charles K. Shafer later testified (p. 208): "... Dr Triffet showed yesterday ... a 
multimegaton detonation [Redwing-Tew a\ in the Pacific in which there was a tremendous fanning out of the fallout ... We do 
not have that type of wind behavior in the United States except possibly in the Gulf States in the summertime ...". 

This Dynamic fallout model was the precursor to DELFIC, the U. S. Department of Defense's Land Fallout Interpretative 
Code, and it included some of the key features. The "Dynamic" in its name is due to its analysis of fallout from the time of 
creation, through the sweep-up process in the mushroom stem updraft, to deposition: "Large particles reach their maximum 
altitude and are falling while smaller particles are still rising." 



In the Jangle-Sugar test fallout pattern there was little wind shear at the cloud altitude, and the mean vector wind velocity from 
thr ground to the cloud top was 40 km/hour. The maximum dose rate from fallout (outside of crater) was 540 R/hr at 1 hour, 
which occurred 900 feet downwind. Dose rates of 500, 300, and 100 R/hr occurred 2,200, 4,900, and 12,500 feet downwind at 
1 hour after detonation. The Jangle-Uncle test was a similar 1.2 kt device detonated 5.2 metres underground in Nevada soil, 
where the mean vector wind velocity was 20 km/hour. The surface wind was only 3.2 km/hour, which allowed the ground 
level "base surge" to carry radioactivity a considerable distance upwind (a factor which Anderson did not include in his fallout 
prediction, which assumed it to be a surface burst). The maximum dose rate from fallout (outside the crater) was 3,400 R/hr, 
which occurred 930 feet downwind. Dose rates of 1,000, 500, 200 and 100 R/hr occurred 1,250, 3,500, 10,000, and 17,200 
feet downwind at 1 hour after detonation. Anderson's Dynamic model predicts that a 1 megaton fission Nevada soil surface 
burst under 10 knot mean winds will produce a maximum downwind 1 hour dose rate hotspot of 6,126 R/hr at 6.9 km 
downwind. Doubling the windspeed reduces this hotspot dose rate by factor of 1.64 (by dispersing the same fallout over a 
larger area), but increases the downwind distance of the peak dose rate by factor of 1.49. Doubling the weapon yield only 
increases the maximum dose rate by a factor of 1.18, but increases its downwind distance by a factor of 1.34. 



Weather Bureau Testimony of Dr W. W. Kellogg (RAND Corp.) to U.S. Congress 

fallout distribution The Nature of Radioactive Fallout and Its Effects on Man, 
predicted at H-2 hours 1957f Part 1, pp . 113-4. 



/ Imr/hr at H 4- 12 hrs 




observed fallout 
distribution 
(dashed lines) 



Nevada test site 
• ground zero 

May 5, 1955 



Weather Bureau 
hand computation 
with time and 
space variation 
of winds 







30 



Statute miles 



60 

-J 




Kmr/hr at H+12 hrs 



/ observed fallout 
/ distribution 
(dashed lines) 



. 'Nevada test site 
'• ground zero 

May 5, 1955 



Figure 14: Teapot-Apple 2 fallout predictions and result, 5 May 1955: Nevada Test Site, burst on the top of a 500 foot high 
steel tower burst, 29 kt total yield (100% fission yield). Solid lines show fallout predictions by Kenneth Nagler of the U.S. 
Weather Bureau, for winds forecast 2 hours before detonation (left), and for wind variations in space and time (right). 
Meteorologist Dr William W. Kellogg of the RAND Corporation presented the fallout patterns in his testimony to the U.S. 
Congressional Hearings before the 1957 Special Subcommittee on Radiation, The Nature of Radioactive Fallout and Its Effects 
on Man, pp. 104-41, where he states that Kenneth Nagler and Dr Lester Machta of the U. S. Weather Bureau found that (for 
12-18 kt tests), the local fallout percentage (activity deposited within 200 miles of ground zero) was 10.8 % for the average of 
five 300-foot steel tower bursts, 5.4 % for a 500 foot steel tower burst (14 kt Teapot-Apple 1) and 1.0 % for an air burst at 524 
feet (the 15 kt Grable test in 1953), compared to 87 % for the 1.2 kt Jangle-Sugar Nevada surface burst in 1951, 85 % for the 
1956 Redwing coral surface bursts (Zuni and Tewa), and 65-10% for Redwing ocean surface bursts (Flathead and Navajo). 

3.53 Mt coral surface burst REDWING-ZUNI: close-in fallout fractionation factors 



Ce-144 
sec Xe) 



0.01 
0.1 



SOURCE: 
WT-1317, 
Fig. 3.32. 
I I I I I 




(Precursors in Parenthesis) 

AVERAGE LAGOON AREA COMPOSITION 



La-140 
sec Xe) 

Sr-90 " 
sec Kr) 



Sr-89 
(192 sec Kr) 



1 10 100 

HALF-LIFE OF PRECURSOR (SECONDS) 



Figure 15: close-in fallout from surface bursts is fractionated, with greatly reduced abundances of the soluble volatile fission 
product like iodine-131, which can only plate the outer surfaces of fallout particles in the later stages of fireball condensation. 
This graph is from Terry Triffet and Philip D. LaRiviere's report Operation Redwing, Characterization of Fallout, WT-1317, 
1961. It shows that there is a correlation between fractionation and the half-life of the volatile precursor in each decay chain. 



PARTICLE FORMATION 



LAND BURST PARTICLES 

-*' CONDENSED PAGTICLES 

i4 




MELTED ENVIRONMENTAL MATERIALS 

Melted, insoluble solid containing 
air bubbles and mineral grains 




WATER BURST PARTICLE 

SALT CRYSTALS SALT 
WATEK 




ENVIRONMENTAL 
MATERIALS 



INITIALS 



INSOLUBLE SOLIDS 

Salt slurry translucent 
white soluble droplet 



Figure 16: lethal fallout is not an invisible gas that can only be detected by special instruments. It must be carried down from 
high altitudes rapidly on large particles in order to produce high doses before the radioactivity decays. Only the Marshallese 
who saw visible fallout deposited from the 1954 Castle-Bravo 14.8 megaton coral reef surface burst 115 miles away received 
beta burns to bare skin, and they were burned only on moist areas of skin and coconut oil dressed hair that retained fallout for 
many hours. Because ordinary clothing did not retain the dry fallout particles, clothed areas were protected from beta radiation 
exposure. However, waterproof clothing is required for protection against wet sticky fallout particles from water surface bursts 
in humid air. (Illustration adapted from Dr Triffet's testimony before the Special Subcommittee on Radiation, June 1959.) 




A HEAVY 

COLLECTION 

FAR OUT 

15 MINUTE EXPOSURE 

TRAY NO 411 

YAG 40, B-7 
ZUNI 



A HEAVY 
COLLECTION 
CLOSE IN 
15 MINUTE EXPOSURE 

TRAY NO. 1204 

YFNB 13.E-57 
ZUNI 




Figure 17: surface bursts loft hundreds of tons of soil/kt as fallout, so the specific activity per unit mass of fallout is relatively 
low, and the carrier soil makes the fallout clearly visible where there is a lethal hazard. You do not need radiation meters to 
determine that a lethal fallout hazard exists. These 8.1 cm-diameter trays were exposed for just 15 minutes (report WT-1317). 



EFFECTIVE ARRIVAL TIME (HOURS) 
8 ? 10 JUL 



-r 



T 



■+- 



1,2 



H 



15 16 17 18 19 20 



-i- 



BRAVO 



Estimated total-dose contours in roentgens at 96 hours 
-100- 
-300, 
*1000 




bqcar0 61 

ATOLL 



'170 

bikini 

ATOLL 



20 



—4— 
40 



AILINGINAE ATOLL 



60 



80 



100 



120 



140 



160 



180 



200 



220 



240 



260 



280 



300 



320 



340 



DISTANCE FROM GROUND ZERO (MILES) 

Figure 18: surface burst Castle-Bravo on 1 March 1954 contaminated downwind inhabited atolls (Glasstone and Dolan). Note 
the effective arrival time of 1 hour near ground zero: the mean fallout arrival time in the lagoon was 28 minutes, but the fallout 
dose rate peaked at 1 hour and material continued arriving for 2 hours, as stated in report WT-915. The fallout forecasting 
error was mainly due to unexpectedly high yield, since was known at before the test that Rongelap and Rongerik were 
downwind. Operation Castle, Radiological Safety, Final Report, volume II (ADA995409, 1985, pages K3-K7): "At the 
midnight weather briefing, the forecast offered a less favorable condition in the lower levels (10,000 to 25,000 feet). Resultant 
winds at about 20,000 feet were forecast in the direction of Rongelap and Rongerik; however, it was considered that the speeds 
and altitudes did not warrant a conclusion that significant quantities and levels of debris would be carried out so far." The 
March 1957 University of Utah Master of Science thesis by meteorologist Frank Cuff, A Study of the Time Variability of 
Integrated Winds Near Las Vegas, Nevada, showed that mean vector wind direction from the surface to 20,000 feet (measured 
by tracking the direction of weather balloon while it rises at a constant rate) varied by an average of only 12 degrees over a 3 
hour period and 22 degrees over a 6 hour period, while even smaller variations occurred for the mean vector wind direction 
between the surface and 50,000 feet: 6 degrees over 3 hours and 13 degrees over 6 hours. The smaller average variation that 
occurs over the larger altitude range is due to the overall cancellation of the effects of some random shifts in wind directions by 
opposing changes at different altitudes: this is relevant to fallout prediction where the "hotline" or axis of maximum activity is 
determined by fallout concentrated at the lower portion of the mushroom cloud. Schuert states in USNRDL-TR-139, 1957: 
"The height lines describing the fallout from the lower portion of the mushroom immediately establish the 'hot line'." 




10 10* 

TIME (HR) 

Figure 18: surface burst radioactivity decay rates depend on fractionation and neutron induced activities such as Np-239 and 
U-237 produced by neutron capture reactions with U-238 in the bomb. But Zuni (3.53 Mt 15% fission coral island surface 
burst), Tewa (5.01 Mt 87% fission coral reef surface burst), Flathead (365 kt 73% fission ocean surface burst) and Navajo 
(clean 4.5 Mt 5% fission ocean surface burst) led to a fractionated (lagoon) and unfractionated (cloud) fallout decay -(time) 



1.2 







Measured 


capture to fission ratios in nuclear tests* 
















Number of neutron capture 


atoms per fission 


Test shot 


Weapon design 


Yield 




Fission % 


U-239 & Np-239 


U-237 


U-240 & Np-240 


Jangle-Sugar 


U238 reflector 


1.2 kt 




100 


0.59 






Jangle- Uncle 


U238 reflector 


1.2 kt 




100 


0.59 






Castle-Bravo 


U238 pusher 


14.8 Mt 




68 


0.56 


0.10 


0.14 


Castle-Romeo 


U238 pusher 


11 Mt 




64 


0.66 


0.10 


0.23 


Castle-Koon 


U238 pusher 


110 kt 




91 


0.72 


0.10 




Castle- Union 


U238 pusher 


6.9 Mt 




72 


0.44 


0.20 


0.07 


Redwing-Zuni 




3.53 Mt 




15 


0.31 


0.20 


0.005 


Redwing-Tew a 




5.01 Mt 




87 


0.36 


0.20 


0.09 


Diablo 


U238 in core** 


18 kt 




100 


0.10 






Shasta 


U238 in core** 


16 kt 




100 


0.10 






Coulomb C 


U238 in core** 


0.6 kt 




100 


0.03 






* Data is derived from all analyses of aircraft cloud fallout 


samples and deposited fallout samples in Dr Carl F. Miller, U.S. Naval Radiological Defense 


Laboratory, report USNRDL-466 (1961), Table 6. 












**In these Plumbbob weapon tests, there was no U238 reflector and the only U238 


in the bomb was that contained 


in the fissile core as an impurity. 



Measured relationship between the fusion yield of the nuclear explosive and the quantity of neutron-induced activities 

in the fallout* 



Test 




Redwing-Navajo 


Redwing-Zuni 


Redwing-Tew a 




Design 




Lead pusher 


Lead pusher 


U-238 pusher 




Total yield 


4.5 Mt 


3.53 Mt 


5.01 Mt 




% Fission 


5 


15 


87 




% Fusion 


95 


85 


13 




Nuclide 


Half life 


Abundance of nuclide 


in bomb fallout, atoms 


per bomb fission 


#7** 


Na-24 


15 hours 


0.0314 


0.0109 


0.00284 


1284.7 


Cr-51 


27.2 days 


0.0120 


0.0017 


0.00030 


0.280 


Mn-54 


304 days 


0.10 


0.011 


0.00053 


0.614 


Mn-56 


2.58 hours 


0.094 




0.00053 


2668 


Fe-59 


45.2 days 


0.0033 


0.00041 


0.00017 


6.19 


Co-57 


272 days 


0.00224 


0.0031 


0.00018 


0.113 


Co-58 


71 days 


0.00193 


0.0036 


0.00029 


3.11 


Co-60 


5.27 years 


0.0087 


0.00264 


0.00081 


0.299 


Cu-64 


12.8 hours 


0.0278 


0.0090 


0.0023 


89.5 


Sb-122 


2.75 days 




0.219*** 




38.4 


Sb-124 


60 days 




0.073*** 




6.92 


Ta-180 


8.15 hours 


0.038 


0.0411 




35.9 


Ta-182 


114 days 


0.038 


0.0326 


0.01 


2.67 


Pb-203 


52 hours 


0.0993 


0.050 


0.000018 


26.0 


U-237 


6.75 days 




0.20 


0.20 


6.50 


U-239 


23.5 minutes 


0.085 


0.31 


0.36 


173 


Np-239 


56.4 hours 


0.085 


0.31 


0.36 


14.9*+* 


U-240 


14.1 hours 




0.005 


0.09 


(no gamma rays) 


Np-240 


7.3 minutes 




0.005 


0.09 


150 



*Dr Terry Triffet and Philip D. LaRiviere, "Characterization of Fallout, Operation Redwing, Project 2.63," U.S. Naval Radiological Defense Laboratory, 

1961, report WT-1317, Table B.22. Data on U-238 capture nuclides is from USNRDL-466, Table 6, in combination with WT-1315, Table 4.1. 

**Triffet's 1961 values for the gamma dose rate at 1 hour after burst at 3 ft above an infinite, smooth, uniformly contaminated plane, using an ideal measuring 

instrument with no shielding from the person holding the instrument, from 1 atom/fission of induced activity, (R/hr)/(fission kt/square stat mile). 

***The Zuni bomb contained a lot of antimony (Sb), which melts at 903. 7K and boils at 1650K. The abundances of Sb-122 and Sb-124 given in the table are 

for unfractionated cloud samples; because of the low boiling point of antimony, it was fractionated in close-in fallout, so the abundances of both Sb-122 and 

Sb-124 in the Zuni fallout at Bikini Lagoon were 8.7 times lower than the unfractionated cloud fallout. 

*+*Note that Np-239 at 1 hour after burst is still forming as the decay product of U-239. 



Figure 19: The low energy of gamma rays from Np-239 and U-237 in the first couple of weeks makes it easier to shield 
gamma from U-238 cased u dirty ,} weapons. The original anti-civil defense propaganda on fallout in the 1950s and 1960s 
originated from false claims about neutron induced activity affecting the decay rate of the fallout substantially for salted or 
cobalt-60 weapons, e.g. Shute's novel On the Beach and the Kubrick film Dr Strangelove. But for each neutron used for the 
fission of U-238 you get 200 MeV of energy, including far more residual radioactivity energy than from capturing the neutron 
in cobalt- 59 to produce cobalt-60. The smaller dose of gamma ray energy from the cobalt-60 gets spread over a longer period 
of time, producing smaller dose rates, enabling decontamination to wash the fallout away before a high dose is accumulated. 




\ v/ ; :-'- ; v ? :? ': ; '• ' -. ' ^w - ^? - yffl'-',"^ • ' - ' »^. - 1 ? ■ ! >•■ ? ? ; 






Figure 20: At 1 metre height above a uniformly contaminated smooth, unobstructed surface, 90% of the gamma dose rate is 
from direct gamma rays and 10% is from air scatter. Some 50% of this gamma radiation dose is contributed by the fallout 
deposited beyond a radius of 15 metres, so the average angle of the gamma rays contributing most of the dose is almost 
horizontal. The air scattered gamma rays have a wide distribution of angles, and are not all coming down vertically, so some 
of them are also absorbed. This is why typically 90% (i.e. the direct gamma ray dose) is stopped in any below ground 
depression such as a narrow ditch or trench. The fallout directly under your feet contributes a negligible proportion to your 
dose, owing to the long range of gamma rays in air. Fallout directly under your feet contributes an insignificant percentage of 
the dose. Even if there is fallout blown into a house through blast shattered windows, the walls will continue to shield the 
major portion of the radiation dose, which is from the direct gamma rays from a wide area outdoors (Kearny, ORNL-5037). 

Spectrum of fission product gamma rays from the thermonuclear neutron fission of U-238 (Glenn R. Crocker, 

Radiation Properties of Fractionated Fallout; Predictions of Activities, Exposure Rates and Gamma Spectra for Selected 

Situations, U.S. Naval Radiological Defense Laboratory, USNRDL-TR-68-134, 27 June 1968, 287 pp.) 



Gamma 


Fission 


product gamma spectrum at 1 hour 


Fission 


product gamma spectrum at 1 week 


ray 


Sr-89 abundance (relative 


to unfractionated fallout) 


Sr-89 abundance (relative 


to unfractionated fallout) 


energy, 


10% 


50% 


100% 


200% 


10% 


50% 


100% 


200% 


MeV 


^89,95 = 0-1 


^89,95 = 0-5 


^89,95 =1* 


^89,95 = 2 


^89,95 = 0-1 


^89,95 = 0.5 


^89,95 =1* 


^89,95 = 2 


0-0.5 


0.396 


0.354 


0.350 


0.304 


0.695 


0.662 


0.678 


0.637 


0.5-1 


0.385 


0.379 


0.363 


0.357 


0.262 


0.270 


0.245 


0.265 


1-1.5 


0.1605 


0.1863 


0.1914 


0.232 


0.01339 


0.01358 


0.01218 


0.01273 


1.5-2 


0.0327 


0.0466 


0.0558 


0.0596 


0.0287 


0.0519 


0.0591 


0.0790 


2-2.5 


0.01628 


0.0203 


0.0279 


0.0290 


0.001114 


0.001313 


0.001268 


0.001445 


2.5-3 


0.00429 


0.00717 


0.01192 


0.01305 


0.001372 


0.00253 


0.00291 


0.00388 


3-3.5 


0.00340 


0.00301 


0.00267 


0.00273 


0.0000260 


0.0000490 


0.0000564 


0.0000760 


3.5-4 


0.001425 


0.001187 


0.001705 


0.00214 















Total: 



1.00 



1.00 



1.00 



1.00 



1.00 



1.00 



1.00 



1.00 



Relative 

gamma 

activity 



0.547 



0.756 



1.25 



0.563 



0.768 



1.12 



Mean 
energy, 

MeV 



0.710 



0.767 



0.807 



0.856 



0.444 



0.486 0.483 



0.526 



-T2- 



1.1 — 



1.0 



0.9 



0.8 

Z 

o 

O 0.7 

Q. 
> 



0.6 



0.5 



0.4 



0.3 



0.2 



' |"H| | I I | M ll| | I I | MH| 1 



EFFECTS OF FRACTIONATION AND NEUTRON INDUCED 
ACTIVITY ON GAMMA RAY ENERGY OF FALLOUT - 

Sources: DrC. S. Cook, Health Physics, v4 (1960), pp42-51 
Dr T. Triffet, Testimony in the U.S. Congressional 
Hearings, Special Subcommittee on Radiation, — 
Joint Committee on Atomic Energy, June 1959, 
"Biological and Environmental Effects of Nuclear War" 



Na-24 effect 




Data points are Nal (Tl) gamma spectrometry 



Unfractionated U-235, thermalized neutrons 
% (DrC. F. Miller, USNRDL-TR-247, 1958) 



95 km downwind 
from REDWING-TEWA 



V •>♦.* 



Np-239 effect # T%~* 

(all bombs with U-238 tamper)^ 



■ ' ■ I i ■"! I i i I mil 




12.6 km downwind 

''from REDWING-TEWA 



Np-239 + U-237 _ 

fc (H-bombs with U-238 
fusion charge pusher) 
I ljljj "■! I i i I nil 



10 



20 



50 100 200 

TIME (hr) 



500 1,000 2,000 5,000 10,000 



10" 1 b- 



10 



O 

\- 
o 
< 

u_ 



y 10 
< 



-4 - 



10 



io- 5 r 



10' 



,-6 



^ 


PENETRATION OF UNFRACTIONATED U-235 FISSION PRODUCT GAMMA DOSE RATE IN CONCRETE = 

^ Source: L. K. Donovan and A. B. Chilton, "Dose Attenuation Factors for Concrete Slab Shields Covered 1 


- 


1^^ with Fallout, as a Function of Time after Fission", U.S. Naval Civil Engineering Lab, report R-137, 1961 ' 
^sftv (Uses spectra published by A. T. Nelms and J. W. Cooper in Health Physics, v1 , 1 959, pp427-41 .) " 


: 




CHILTON & SAUNDERS (1.0 MeV) = 


— 




^^fe*. 


— 


— 






w 1.12 HRS " 

^4L i 


: 






^S^^O^v. 2.11 DAYS \ 








^s/^^g^v^ 23.8 HRS 


■ 






4.57 DAYS^^S. ^^^^J/^\^ : 


- 






208 DAYS^ ^S. ^^^^^O^^n. " 


2 








- 


1 


I 1 1 


I.I.I >. I 



2 _ 



■3 _ 



0.5 



1.0 1.5 2.0 

THICKNESS OF CONCRETE (feet) 



2.5 



3.0 



Figure 21: fallout radiation protection factor calculations are traditionally made assuming the 1.25 MeV mean gamma ray 
energy of cobalt-60, not the wider spectrum of actual gamma rays from bomb fallout. This leads to substantial underestimates 
of protection factors which are smaller than 100. The effect of Np-239 and U-237 (which make a maximum percentage 
contribution to t" 1 ' 2 fallout decay radiation at a time of 1.2/ln2 = 1.73 times their respective half-lives of 56 hours and 6.8 days, 
i.e. 97 hours and 12 days, respectively) further softens the gamma ray spectrum, increasing the benefits of any shielding, as 
explained by Operation Redwing fallout characterization project officer Dr Terry Triffet to congress in June 1959. 



Dr Triffet at the 22-26 June 1959 Congressional Hearings on the Biological and Environmental Effects of Nuclear War pages 
61-111 showed that at 1 week after burst, the mean gamma ray energy of fractionated fallout 8 statute miles downwind of a 
megaton range surface burst was 0.25 MeV, while at 60 statute miles downwind it was 0.35 MeV (due to less depletion of high 
energy fission products at greater distances, a fractionation effect). On page 205 of the June 1959 hearings on the Biological 
and Environmental Effects of Nuclear War, Dr Triffet explained that the low gamma ray energy makes most of the radiation 
very easy to shield by improvised emergency countermeasures: 

"I thought this might be an appropriate place to comment on the variation of the average energy. It is clear when you think of 
shielding, because the effectiveness of shielding depends directly on the average energy radiation from the deposited material. 
As I mentioned, Dr Cook at our [U.S. Naval Radiological Defense] laboratory has done quite a bit of work on this. ... if 
induced products are important in the bomb [i.e. in high fission devices employing U-238 ablative "pushers" or fusion capsule 
jackets], there are a lot of radiations emanating from these, but the energy is low so it operates to reduce the average energy in 
this period and shielding is immensely more effective." 

There is extensive data on the gamma ray spectrum of fallout from the Zuni, Tewa, Flathead and Navajo surface bursts in 
Table B.21 of Triffet and LaRiviere's 1961 report Characterization of Fallout (WT-1317) and in Tables 1 and 2 of W. E. 
Thompson's report Spectrometric Analysis of Gamma Radiation from Fallout from Operation Redwing (U. S. Naval 
Radiological Defense Laboratory technical report USNRDL-TR-146, 1957). For example, Thompson gives the detailed 
spectrum of gamma radiation measured on Bikini Island (codenamed How Island, fallout collector F-61, sample GA) at 13 
miles east-north-east of ground zero for the 3.53 Mt 15% fission coral surface burst Zuni. At 10 days after this detonation, the 
mean gamma ray energy emitted by this sample was just 0.218 MeV. Since shielding thicknesses are roughly proportional to 
the square root of the gamma ray energy, shielding thicknesses needed for a given protection factor at this time were 2.4 times 
smaller than for cobalt-60 gamma radiation (1.25 MeV mean). 

Zuni fallout gamma ray spectrum measured at 10 days after detonation, 13 miles downwind (sample How F-61 GA)* 



Gamma ray energy (MeV) 




% of gamma rays emitted by fallout sample 




0.060 




15.5 




0.105 




38.8 




0.220 




19.4 




0.280 




9.3 




0.330 




3.8 




0.500 




3.9 




0.650 




3.1 




0.750 




6.2 





Mean energy 0.218 MeV 

*W. E. Thompson, Spectrometric Analysis of Gamma Radiation from Fallout from Operation Redwing, U. S. Naval 
Radiological Defense Laboratory technical report USNRDL-TR-146, 29 April 1957, Tables 1 and 2. Note that this is the 
gamma ray spectrum actually measured for a fallout sample placed near the scintillation crystal of a gamma ray spectrometer, 
so it does not include the further reduction in gamma ray energy that occurs from Compton scattering in the atmosphere. 

Ocean water surface burst fallout is unfractionated so it emits slightly higher energy gamma rays. For example, R. L. Stetson's 
report Operation Castle, Project 2.5a, Distribution and Intensity of Fallout, WT-915, 1956, on page 145 states that the 
measured mean gamma ray energy of a fallout sample from the 13.5 Mt 52% fission Castle-Yankee ocean surface burst was 
0.344 MeV at 8 days after detonation. Nevertheless, this is still substantially less than the 1.25 MeV mean energy of the 
cobalt-60 gamma rays assumed in most protection factor calculations, and is only about half of the 0.7 MeV figure mentioned 
by Glasstone. (The Castle-Yankee U-238 neutron capture nuclide abundances are similar to those for Castle-Romeo in Figure 
19 above.) 

Further reading on the effects of nuclear weapons 



Bridgman, Charles J., Introduction to the Physics of Nuclear Weapons Effects, DTRA, 2001. 

Dolan, Philip J., Capabilities of Nuclear Weapons, DNA-EM-1, 2 volumes, 1972, change 1 (1978), change 2 (1981). 

Glasstone, Samuel, and Philip J. Dolan, Effects of Nuclear Weapons, 3 rd ed., 1977. 

Northrop, John A., Handbook of Nuclear Weapon Effects: Calculational Tools Abstracted from DSWA's Effects Manual One 

(EM -I), Defense Special Weapons Agency, 1996. 
Military Research and Development Subcommittee, Committee on Armed Services, Electromagnetic Pulse Threats to U. S. 

Military and Civilian Infrastructure, Published record of Congressional Hearings held on 7 October 1999. 
Special Subcommittee on Radiation, Joint Committee on Atomic Energy, Biological and Environmental Effects of Nuclear 

War, Published record of Congressional Hearings held from 22-26 June 1959. 
Special Subcommittee on Radiation, Joint Committee on Atomic Energy, Nature of Radioactive Fallout and Its Effects on 

Man, Published record of Congressional Hearings held from May- June 1957.